<%@ page language="java" contentType="text/jpeg" pageEncoding="UTF-8" %>
<%@ page import="javax.imageio.*" %>
<%@ page import="java.awt.*" %>
<%@ page import="java.awt.image.*" %>
<%@ page import="java.util.*" %>
<%!
	Color getRandColor(int fc, int bc) {
		Random random = new Random();
		
		if(fc > 255) {
			fc = 255;
		}
		if(bc > 255) {
			bc = 255;
		}
		
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		return new Color(r, g, b);
	}
%>

<%
	out.clear();
	response.setHeader("Pragma", "No-cache");
	response.setHeader("Cache-Control", "no-cache");
	response.setDateHeader("Expires", 0);
	
	int width = 60, height = 20;
	BufferedImage image=  new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
	Graphics g = image.getGraphics();
	Random r = new Random();
	
	g.setColor(getRandColor(200, 250));
	g.fillRect(0, 0, width, height);
	g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
	g.setColor(getRandColor(160, 200));
	
	for(int i = 0; i < 155; i++) {
		int x1 = r.nextInt(width);
		int y1 = r.nextInt(height);
		int x2 = r.nextInt(12);
		int y2 = r.nextInt(12);
		g.drawLine(x1, y1, x1 + x2, y1 + y2);
	}
	
	String sRand = "";
	for(int i = 0; i < 4; i++) {
		String rand = String.valueOf(r.nextInt(10));
		sRand += rand;
		g.setColor(new Color(20 + r.nextInt(110), 20 + r.nextInt(110), 20 + r.nextInt(110)));
		g.drawString(rand, 13 * i + 6, 16);
	}
	
	// 将验证码存入Session
	session.setAttribute("sRand", sRand);
	g.dispose();
	ImageIO.write(image, "JPEG", response.getOutputStream());
%>